Effect of Composition on Designed Tandem Absorber to Achieve Selective Properties for High Temperature Solar Thermal Applications

Abstract

We have designed a tandem absorber comprising of five layers namely:TiAlC / TiAlCN / TiAlSiCN / TiAlSiCO / TiAlSiO on stainless steel substrate by DC unbalanced magnetron sputtering system.Tandem absorber shows a high absorptance of 0.961 with an emittance of 0.15 by careful optimization of flow rates and thicknesses of the individual layers. Further, the detailed effects of reactive gas flow rates and thicknesses of each individual layers on the optical properties were studied. Growth rate and thicknesses of each individual layers of the tandem absorber were studied by cross-section FESEM images. The tandem absorber shows long term thermal stability when annealed in vacuum at 600°C for more than 750 h under cyclic heating conditions, indicating suitability of the tandem absorber for solar thermal high temperature applications